Cell manipulation with magnetic particles toward microfluidic cytometry

Abstract

Magnetic particles have become a promising tool for nearly all major lab-on-a-chip (LOC) applications, from sample capturing, purification, enrichment, transport to detection. For biological applications, the use of magnetic particles is especially well established for immunomagnetic separation. There is a great amount of interest in the automation of cell sorting and counting with magnetic particles in LOC platforms. So far, despite great efforts, only few fully functional LOC devices have been described and further integration is necessary. In this review, we will describe the physics of magnetic cell sorting and counting in LOC formats with a special focus on recent progress in the field.

Continuous-flow ferrohydrodynamic sorting of particles and cells in microfluidic devices

“…Magnetophoresis (MAP) takes advantages of paramagnetic nature of red blood cells and magnetotactic bacteria and applies non-uniform magnetic fields to separate them from non-magnetic objects (Zborowski et al 2003; Lee et al 2004). However, most applications of magnetophoresis use functionalized magnetic beads for labeling (Pamme 2006;Liu et al 2009;Gijs et al 2010). The label-based methods are manually intensive and time-consuming.…”

Optical particle sorting on an optofluidic chip

“…The ability to do this sorting on chip is ideal since it requires less handling of the sample and allows for smaller sample sizes. Previously reported sorting schemes involve optical [1][2][3], magnetic [4,5], electrical [6,7], acoustic [8,9] or mechanical [10][11][12] methods of separating objects by size or index, with sorting efficiencies ranging from 75% to 100%. Some of these options require an aspect of detection before separation [4,13], adding unwanted complexity.…”

“…Previously reported sorting schemes involve optical [1][2][3], magnetic [4,5], electrical [6,7], acoustic [8,9] or mechanical [10][11][12] methods of separating objects by size or index, with sorting efficiencies ranging from 75% to 100%. Some of these options require an aspect of detection before separation [4,13], adding unwanted complexity. Recently, optofluidic sorting based on microparticle manipulation by evanescent fields was demonstrated by using optical gradient forces to draw particles from a fluidic channel onto a microring resonator [14][15][16].…”

Actuation and tracking of a single magnetic particle on a chip

“…1,2 Due to their magnetic properties and small dimension, they offer possibilities to label, actuate, and separate on the micron and submicron scale. [3][4][5][6][7] The force exerted on a particle with a magnetic dipole moment m when exposed to a magnetic field B is given by F mag 5 (mÁ$)ÁB. For superparamagnetic particles, the magnetic moment is m 5 l 0 À1 VvB, where l 0 is the vacuum permeability, V is the volume of the particle, and v is the magnetic susceptibility of the particle.…”